Is there a "better" (signal-based) language for artificial intelligence
What You need are other ways of knowledge representation, such as semantic networks or conceptual graphs. there you can define any possible relation between your entities. the knowledge of "x related to 4" exactly fits into "frames" and "semantic networks". 
Jaynes in his book,discusses thoroughly what "plausibility" means and why we need to take into account weak syllogisms and start using probability theory as a platform for developing a (general) AI. this might also help with your "reasoning" phase (after you've developed your knowledge base)